TW202300399A - Front sprocket assembly for a human-powered vehicle - Google Patents

Abstract

A front sprocket assembly 34 comprises a first sprocket 51 and a second sprocket 53. The second sprocket 53 includes a plurality of second sprocket teeth 71. The plurality of second sprocket teeth 71 includes at least one second reference tooth 73 and at least one chain-holding tooth 75. The at least one chain-holding tooth 75 is disposed at a downstream side of the at least one second reference tooth 73. The at least one chain-holding tooth 75 has an axially outward chamfer 75b and an axially inward chamfer 75c. The inward-chamfer end 75e2 of the axially inward chamfer 75c of the at least one chain-holding tooth 75 is disposed radially outwardly from the outward-chamfer end 75e1 of the axially outward chamfer 75b of the at least one chain-holding tooth 75 with respect to the rotational center axis X1.

Description

Sprocket assembly before being used in human transportation

The present invention relates to a front sprocket assembly for a human vehicle.

Cycling is becoming an increasingly popular form of recreation as well as a mode of transportation. Furthermore, cycling has become a very popular competitive sport for both amateurs and professionals.

Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various systems of the bicycle. A bicycle system has been extensively redesigned for use with a front sprocket assembly of a human vehicle, especially to achieve smooth shifting operations. Before being used in a human vehicle, the sprocket assembly is used to be installed on a frame of the human vehicle.

According to a first aspect of the present invention, a front sprocket assembly for a human vehicle includes a first sprocket and a second sprocket.

The first sprocket has a first axially outward surface and a first axially inwardly disposed on an opposite side of the first axially outward surface in an axial direction relative to a rotational center axis. surface.

The first sprocket includes a first sprocket body and a plurality of first sprocket teeth. The plurality of first sprocket teeth extend radially outward from a first outer periphery of the first sprocket body in a radial direction relative to the rotation center axis. The plurality of first sprocket teeth includes at least one first reference tooth.

The second sprocket has a second axially outward surface and a second axially inward surface disposed on an opposite side of the second axially outward surface in the axial direction.

The second axially inward surface is configured to face the first axially outward surface of the first sprocket in the axial direction in an assembled state of the front sprocket assembly.

The second sprocket includes a second sprocket body and a plurality of second sprocket teeth. The plurality of second sprocket teeth extend radially outward from a second outer periphery of the second sprocket body in the radial direction. The plurality of second sprocket teeth includes at least one second reference tooth and at least one chain retaining tooth.

The first sprocket has a first pitch diameter. The second sprocket has a second pitch diameter greater than the first pitch diameter. The second sprocket is adjacent to the first sprocket and there is no other sprocket between the first sprocket and the second sprocket in the axial direction.

The at least one first reference tooth is configured to first mesh with a chain during a downshift operation in which the chain shifts from the second sprocket toward the first sprocket such that the at least one first reference tooth A non-drive surface contacts a chain roller of the chain. The at least one second reference tooth is configured to disengage first an inner link plate of the chain during the downshift operation.

The at least one chain holding tooth is configured to be positioned at a downstream side of the at least one second reference tooth relative to a drive rotation direction of the front sprocket assembly such that the at least one chain holding tooth train is from the at least one One of the even-numbered teeth of the second reference tooth.

The at least one chain retaining tooth has a tooth tip, an axially outward chamfer disposed to the second axially outward surface, and an axially inward chamfer disposed to the second axially inward surface.

The axially outward chamfer extends radially inwardly from the tooth tip to an outwardly chamfered end relative to the rotation center axis. The axially inward chamfer extends radially inwardly from the tooth tip to an inwardly chamfered end relative to the rotation center axis. The inwardly chamfered end is disposed radially outwardly from the outwardly bevelled end relative to the central axis of rotation.

In the case of the previous sprocket assembly according to the first aspect, the at least one first reference tooth first meshes with the chain in the downshifting operation such that the non-drive face of the at least one first reference tooth is in contact with the chain of the chain. Chain roller contact. During the downshifting operation, the at least one second reference tooth first disengages from the inner link plate of the chain.

The at least one chain holding tooth is disposed at the downstream side of the at least one second reference tooth with respect to the drive rotation direction of the front sprocket assembly. The at least one chain retaining tooth set is from the even numbered teeth of the at least one second reference tooth.

The inwardly chamfered end of the axially inwardly chamfered end of the at least one chain retaining tooth is relative to the rotational center axis from the outwardly chamfered end diameter of the axially outwardly chamfered at least one chain retaining tooth Set outwards.

By configuring the front sprocket assembly such as described above, the at least one chain holding tooth of the second sprocket can securely hold the chain when the chain moves from the second sprocket to the first sprocket. the chain. Thereby, the front sprocket assembly can realize the smooth shifting operation of moving the chain from the second sprocket to the first sprocket.

According to a second aspect of the invention, the sprocket assembly according to the first aspect is configured such that a first radial distance is defined radially from the inwardly chamfered end to the outwardly Chamfered ends. The first radial distance is equal to or greater than 1.0 mm. As for the previous sprocket assembly according to the second aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that shape to set the first radial distance to securely hold the chain.

According to a third aspect of the invention, the sprocket assembly according to the second aspect is configured such that the first radial distance is equal to or less than 2.0 mm. In the case of the previous sprocket assembly according to the third aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain retaining tooth is capable of moving the chain from the second sprocket to the first sprocket. The first sprocket is firmly engaged with the chain by such a configuration as to set the first radial distance.

According to a fourth aspect of the present invention, the sprocket assembly according to any one of the first to third aspects is configured such that the second sprocket has a base circle. A second radial distance is defined radially from the tooth bottom circle to the inwardly chamfered end relative to the rotation center axis. The second radial distance is equal to or greater than 3.0 mm. As for the previous sprocket assembly according to the fourth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that Shape to set the second radial distance to securely hold the chain.

According to a fifth aspect of the present invention, the sprocket assembly before the fourth aspect is configured such that the second radial distance is equal to or less than 5.0 mm. As for the previous sprocket assembly according to the fifth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth can set the second sprocket by such a configuration as The radial distance is firmly engaged with the chain.

According to a sixth aspect of the present invention, according to any one of the first aspect to the fifth aspect, the previous sprocket assembly is configured such that the at least one chain retaining tooth is configured to retain an inner link of the chain plate. As for the previous sprocket assembly according to the sixth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that Shape to configure the at least one chain holding tooth to firmly hold the chain.

According to a seventh aspect of the present invention, according to any one of the first aspect to the sixth aspect, the preceding sprocket assembly is configured such that the at least one chain holding tooth train is from one of the at least one second reference tooth One of the second tooth, one fourth tooth and one sixth tooth. As for the previous sprocket assembly according to the seventh aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that Shape to configure the at least one chain holding tooth to firmly hold the chain.

According to an eighth aspect of the present invention, the sprocket assembly according to the seventh aspect is configured such that the at least one chain holding tooth train is from a fourth tooth of the at least one second reference tooth. As for the previous sprocket assembly according to the eighth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that Shape to configure the at least one chain holding tooth to firmly hold the chain.

According to a ninth aspect of the present invention, the sprocket assembly according to any one of the first aspect to the sixth aspect is configured such that the at least one chain holding tooth includes a plurality of chain holding teeth. The plurality of chain retaining teeth includes at least two teeth from a second tooth, a fourth tooth and a sixth tooth from the at least one second reference tooth. As for the previous sprocket assembly according to the ninth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured by such Shape to configure the at least one chain holding tooth to firmly hold the chain.

According to a tenth aspect of the present invention, the sprocket assembly according to any one of the first to sixth aspects is configured such that the at least one chain holding tooth includes at least three chain holding teeth. The at least three chain holding teeth respectively include at least a second tooth, a fourth tooth and a sixth tooth from the at least one second reference tooth. As for the previous sprocket assembly according to the tenth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be configured such that Shape to configure the at least one chain holding tooth to firmly hold the chain.

According to an eleventh aspect of the present invention, the sprocket assembly according to any one of the first to tenth aspects is configured such that the first sprocket has a first total number of teeth. The second sprocket has a second total number of teeth that is one greater than the first total number of teeth. As for the previous sprocket assembly according to the eleventh aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be activated by such The first sprocket and the second sprocket are configured to firmly hold the chain. Thereby, the front sprocket assembly can realize the smooth shifting operation of moving the chain from the second sprocket to the first sprocket.

According to a twelfth aspect of the present invention, the sprocket assembly according to the eleventh aspect is configured such that a difference between the first total number of teeth and the second total number of teeth is equal to or greater than nine. As for the front sprocket assembly according to the twelfth aspect, the front sprocket assembly can realize a gear shifting system having a wide range by configuring the difference in the number of teeth such as this.

According to a thirteenth aspect of the present invention, according to the eleventh aspect or the twelfth aspect, the sprocket assembly is configured such that the difference in the number of teeth between the first total number of teeth and the second total number of teeth is equal to or less than 20. As for the front sprocket assembly according to the thirteenth aspect, the front sprocket assembly can realize the movement of the chain from the first sprocket to the second sprocket by configuring the difference in the number of teeth by such a configuration. One of the sprockets smooth gear shifts.

According to a fourteenth aspect of the present invention, the previous sprocket assembly according to any one of the eleventh aspect to the thirteenth aspect is configured such that the second total number of teeth is in the range from 48 to 58. As for the front sprocket assembly according to the fourteenth aspect, the front sprocket assembly can realize a drive train having a light weight and a wide range by configuring the second total number of teeth by such a configuration .

According to a fifteenth aspect of the present invention, the sprocket assembly according to any one of the eleventh aspect to the fourteenth aspect is configured such that the first total number of teeth is in the range from 31 to 44. As for the front sprocket assembly according to the fifteenth aspect, the front sprocket assembly can realize the power train with the light weight and the wide range by configuring the second total number of teeth by such a configuration .

According to a sixteenth aspect of the present invention, according to any one of the eleventh aspect to the fourteenth aspect, the previous sprocket assembly is configured such that the at least one first reference tooth is configured so that the The downshifting operation of the chain shifting from the second sprocket toward the first sprocket first engages an inner link plate of the chain. In the case of the previous sprocket assembly according to the sixteenth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain holding tooth of the second sprocket can be activated by such configuration to configure the at least one first reference tooth to securely hold the chain. Thereby, the front sprocket assembly can realize the smooth shifting operation of moving the chain from the second sprocket to the first sprocket.

According to a seventeenth aspect of the present invention, a front sprocket assembly for a human vehicle includes a first sprocket and a second sprocket.

The first sprocket has a first axially outward surface and a first axially inwardly disposed on an opposite side of the first axially outward surface in an axial direction relative to a rotational center axis. surface.

The first sprocket includes a first sprocket body and a plurality of first sprocket teeth. The plurality of first sprocket teeth extend radially outward from a first outer periphery of the first sprocket body in a radial direction relative to the rotation center axis. The plurality of first sprocket teeth includes at least one first reference tooth.

The second sprocket has a second axially outward surface and a second axially inward surface disposed on an opposite side of the second axially outward surface in the axial direction.

The second axially inward surface is configured to face the axially outward surface of the first sprocket in the axial direction in an assembled state of the front sprocket assembly.

The second sprocket includes a second sprocket body and a plurality of second sprocket teeth. The plurality of second sprocket teeth extend radially outward from a second outer periphery of the second sprocket body in the radial direction. The plurality of second sprocket teeth includes at least one second reference tooth and at least one chain retaining tooth.

The first sprocket has a first pitch diameter. The second sprocket has a second pitch diameter greater than the first pitch diameter. The second sprocket is adjacent to the first sprocket and there is no other sprocket between the first sprocket and the second sprocket in the axial direction.

The at least one first reference tooth is configured to first mesh with a chain during a downshift operation in which the chain shifts from the second sprocket toward the first sprocket such that the at least one first reference tooth A non-drive surface contacts a chain roller of the chain.

The at least one second reference tooth is configured to disengage first an inner link plate of the chain during the downshift operation.

The at least one chain holding tooth is configured to be positioned at a downstream side of the at least one second reference tooth relative to a drive rotation direction of the front sprocket assembly such that the at least one chain holding tooth train is from the at least one One of the even-numbered teeth of the second reference tooth.

The at least one chain retaining tooth has a tooth tip, an axially outward chamfer disposed to the second axially outward surface, and an axially inward chamfer disposed to the second axially inward surface.

The axially outward chamfer extends radially inwardly from the tooth tip to an outwardly chamfered end relative to the rotation center axis. The axially inward chamfer extends radially inwardly from the tooth tip to an inwardly chamfered end relative to the rotation center axis.

The second sprocket has a base circle. A radial distance is defined radially from the tooth bottom circle to the inwardly chamfered end relative to the rotation center axis. The radial distance is equal to or greater than 3.0 mm.

In the case of the sprocket assembly according to the seventeenth aspect, the at least one first reference tooth first meshes with the chain in the downshifting operation such that the non-drive face of the at least one first reference tooth and the chain The chain rollers make contact. During the downshifting operation, the at least one second reference tooth first disengages from the inner link plate of the chain.

The at least one chain holding tooth is disposed at the downstream side of the at least one second reference tooth with respect to the drive rotation direction of the front sprocket assembly. The at least one chain retaining tooth set is from the even numbered teeth of the at least one second reference tooth.

The radial distance defined radially from the base circle of the second sprocket to the inwardly chamfered end of the axially inwardly chamfered end of the at least one chain holding tooth relative to the central axis of rotation is equal to or greater than 3.0 mm.

By configuring the front sprocket assembly such as described above, the at least one chain holding tooth of the second sprocket can securely hold the chain when the chain moves from the second sprocket to the first sprocket. the chain. Thereby, the front sprocket assembly can realize the smooth shifting operation of moving the chain from the second sprocket to the first sprocket.

According to an eighteenth aspect of the present invention, the sprocket assembly according to the seventeenth aspect is configured such that the second radial distance is equal to or smaller than 5.0 mm. In the case of the previous sprocket assembly according to the eighteenth aspect, when the chain moves from the second sprocket to the first sprocket, the at least one chain retaining tooth is capable of moving from the second sprocket to the first sprocket. The first sprocket is firmly engaged with the chain by setting the second radial distance through such a configuration.

Those skilled in the art will appreciate from this disclosure that the following descriptions of embodiments of the technology are for illustration only and are not intended to limit the technology as defined by the appended claims and their equivalents.

In the following embodiments, if a plurality of members and parts correspond to each other, the corresponding members and corresponding parts are denoted by the same reference numerals.

As shown in FIG. 1 , a bicycle 1 includes a bicycle chain 3 , a bicycle frame 5 , a handle 7 , a front wheel 9 and a rear wheel 11 , a shift operating device 13 , a drive train 15 and a front fork 17 . The bicycle 1 further includes a bicycle front hub assembly 18 , a bicycle rear hub assembly 19 , a bicycle front derailleur 21 and a bicycle rear derailleur 23 . Bicycle 1 is an example of a human-powered vehicle.

The front fork 17 is rotatably mounted to the bicycle frame 5 . The handle 7 is fixed to the front fork 17 . The bicycle front hub assembly 18 is mounted to the front fork 17 . The front wheel 9 is rotatably mounted to a front fork 17 via a bicycle front hub assembly 18 . A front tire 9a is attached to the front wheel 9 .

The rear wheel hub assembly 19 of the bicycle is installed to the rear part of the bicycle frame 5 . The rear wheel 11 is rotatably mounted to a rear portion of the bicycle frame 5 via a rear bicycle hub assembly 19 . To the rear wheel 11, a rear tire 11a is attached.

A shift operating device 13 is attached to the handlebar 7 . The shift operating device 13 operates the bicycle front derailleur 21 and the bicycle rear derailleur 23 via a control cable such as a Bowden cable or a cable.

The transmission system 15 mainly includes a crank assembly 25 and a bicycle rear sprocket assembly 27 . The bicycle chain 3 may be included in the drive train 15 .

The crank assembly 25 is rotatably supported on a lower portion of the bicycle frame 5 . The crank assembly 25 includes a crank shaft 31 , a pair of crank arms 33 and a front sprocket assembly 34 .

The crankshaft 31 is rotatably supported on the lower portion of the bicycle frame 5 . A crankshaft 31 is mounted to the pair of crank arms 33 . The crankshaft 31 includes a rotation center axis X1.

The pair of crank arms 33 includes a left crank arm 35 and a right crank arm 37 . A left crank arm 35 is mounted to one end of the crank shaft 31 . The left crank arm 35 rotates integrally with the crankshaft 31 . A pedal is mounted to the left crank arm 35 .

As shown in FIG. 2 , the right crank arm 37 is mounted to the other end of the crankshaft 31 . The right crank arm 37 rotates integrally with the crankshaft 31 . Front sprocket assembly 34 is mounted to right crank arm 37 .

As shown in FIG. 3 , the right crank arm 37 includes an arm body 39 and a sprocket mounting portion 41 . The arm body 39 is mounted to the other end of the crankshaft 31 . In this embodiment, the arm body 39 is integrally formed with the sprocket mounting portion 41 . The arm body 39 rotates integrally with the sprocket mounting portion 41 . A pedal is mounted to the arm body 39 .

As shown in FIGS. 2 and 3 , the sprocket mounting portion 41 partially overlaps the first sprocket 51 in the radial direction with respect to the rotation center axis X1. The first sprocket 51 and the second sprocket 53 are mounted to the sprocket mounting portion 41 such that the radially outer end of the sprocket mounting portion 41 is sandwiched by the first sprocket 51 in an axial direction with respect to the rotation center axis X1. and the second sprocket 53.

As shown in FIGS. 2 and 3 , the front sprocket assembly 34 includes a plurality of bicycle front sprockets. For example, the front sprocket assembly 34 includes a first sprocket 51 and a second sprocket 53 . The first sprocket 51 and the second sprocket 53 mesh with the bicycle chain 3 . A detailed explanation of the front sprocket assembly 34 will be described below.

As shown in FIG. 1 , the bicycle front derailleur 21 is mounted to the bicycle frame 5 . For example, a bicycle front derailleur 21 is mounted to a seat tube 6 of a bicycle frame 5 . The bicycle front derailleur 21 moves the bicycle chain 3 from one of the first sprocket 51 and the second sprocket 53 to the other of the first sprocket 51 and the second sprocket 53 in response to the operation of the shift operating device 13 .

The rear sprocket assembly 27 of the bicycle is installed to the rear hub assembly 19 of the bicycle. The bicycle rear sprocket assembly 27 includes a plurality of bicycle rear sprockets. A plurality of bicycle rear sprockets mesh with the bicycle chain 3 .

A bicycle rear derailleur 23 is mounted to the bicycle frame 5 . A bicycle rear derailleur 23 is mounted to a rear portion of the bicycle frame 5 . The bicycle rear derailleur 23 moves the bicycle chain 3 from one bicycle rear sprocket of the bicycle rear sprocket assembly 27 to another bicycle rear sprocket of the bicycle rear sprocket assembly 27 by the shifter 13 .

As shown in FIGS. 2 and 3 , the front sprocket assembly 34 of the bicycle 1 includes a first sprocket 51 and a second sprocket 53 .

As shown in FIG. 4 , the first sprocket 51 is smaller than the second sprocket 53 . For example, a diameter of the first sprocket 51 is smaller than a diameter of the second sprocket 53 .

Specifically, the first sprocket 51 has a first pitch circle diameter P1. The second sprocket 53 has a second pitch diameter P2 that is larger than the first pitch diameter P1. A center of the first pitch circle diameter P1 and a center of the second pitch circle diameter P2 are defined on the rotation center axis X1.

The first sprocket 51 has a first total number of teeth. The first total number of teeth refers to the total number of teeth of one of the plurality of first sprocket teeth 61 . The first total number of teeth is in the range from 31-44. In this embodiment, the first total number of teeth is 34 .

As shown in FIGS. 3 and 4 , the first sprocket 51 has a first axially outward surface 55 and is disposed on one of the first axially outward surfaces 55 in the axial direction relative to the rotation center axis X1. A first axially inward surface 57 on the opposite side. The first sprocket 51 includes a first sprocket body 59 and a plurality of first sprocket teeth 61 .

As shown in FIG. 3 , in an assembled state of the front sprocket assembly 34 , the first axially outward surface 55 is disposed in an axial direction with a first one of the second sprocket 53 shown in FIG. 2 . The two axially inner surfaces 67 are separated by a predetermined distance.

The assembled state of the front sprocket assembly 34 is a state in which the front sprocket assembly 34 (for example, the first sprocket 51 and the second sprocket 53 ) is mounted to the right crank arm 37 .

As shown in FIG. 3 , the first axially outward surface 55 forms an axially outward surface of the first sprocket body 59 and an axially outward surface of the plurality of first sprocket teeth 61 .

As shown in FIG. 4 , in one of the installed states of the front sprocket assembly 34 , the first axially inward surface 57 faces the bicycle frame 5 in the axial direction. The installed state of the front sprocket assembly 34 is a state in which the front sprocket assembly 34 is installed to the bicycle frame 5 . The first axially inward surface 57 forms an axially inward surface of the first sprocket body 59 and an axially inward surface of the plurality of first sprocket teeth 61 .

As shown in FIGS. 2 and 3 , the first sprocket body 59 is formed in a ring shape. The first sprocket body 59 is mounted to the sprocket mounting portion 41 of the right crank arm 37 by the fixing member 46 .

As shown in FIG. 4 , the plurality of first sprocket teeth 61 mesh with the bicycle chain 3 . The plurality of first sprocket teeth 61 extend radially outward from a first outer periphery of the first sprocket body 59 in a radial direction relative to the rotation center axis X1 . The plurality of first sprocket teeth 61 includes at least one first reference tooth 62 .

As shown in FIG. 4 , at least one first reference tooth 62 is configured to first engage with one of the bicycle chain 3 in a downshift operation in which the bicycle chain 3 is shifted from the second sprocket 53 toward the first sprocket 51 . The inner link plate 3a is engaged. For example, in a downshift operation in which the bicycle chain 3 is shifted from the second sprocket 53 toward the first sprocket 51, at least one first reference tooth 62 is first disposed between a pair of inner link plates 3a of the bicycle chain 3 .

Specifically, the at least one first reference tooth 62 is configured to first engage the bicycle chain 3 during a downshift operation in which the bicycle chain 3 shifts from the second sprocket 53 toward the first sprocket 51 such that the at least one first reference tooth 62 A non-drive surface 62a of a reference tooth 62 is in contact with the bicycle chain roller 3b of the bicycle chain 3 .

In this embodiment, as shown in FIG. 5 , at least one first reference tooth 62 includes a plurality of first reference teeth 62a to 62j.

As shown in FIG. 2 , the second sprocket 53 is adjacent to the first sprocket 51 and there is no other sprocket between the first sprocket 51 and the second sprocket 53 in the axial direction.

The second sprocket 53 has a second total number of teeth greater than one of the first total number of teeth. The second total number of teeth refers to the total number of teeth of one of the plurality of second sprocket teeth 71 . The second total number of teeth is in the range from 48-58. In this embodiment, the second total number of teeth is 50 .

A difference in the number of teeth between the first total number of teeth and the second total number of teeth is equal to or greater than 9. A difference in the number of teeth between the first total number of teeth and the second total number of teeth is 20 or less. In this embodiment, the number of teeth differs by 16.

As shown in FIGS. 3 and 4 , the second sprocket 53 has a second axially outward surface 65 and a second axially opposite surface disposed on the opposite side of the second axially outward surface 65 in the axial direction. Inward facing surface 67 . The second sprocket 53 includes a second sprocket body 69 and a plurality of second sprocket teeth 71 .

As shown in FIG. 3 , the second axially outward surface 65 forms an axially outward surface of the second sprocket body 69 and an axially outward surface of the plurality of second sprocket teeth 71 .

As shown in FIG. 4 , the second axially inward surface 67 is configured to face the first axially outward surface 55 of the first sprocket 51 in the axial direction in the assembled state of the front sprocket assembly 34 .

The second axially inward surface 67 forms an axially inward surface of the second sprocket body 69 and an axially inward surface of the plurality of second sprocket teeth 71 .

As shown in FIGS. 2 and 3 , the second sprocket body 69 is formed in a ring shape. The second sprocket body 69 is mounted to the sprocket mounting portion 41 of the right crank arm 37 .

As shown in FIG. 4 , the plurality of second sprocket teeth 71 meshes with the bicycle chain 3 . The plurality of second sprocket teeth 71 extend radially outward from a second outer periphery of the second sprocket body 69 in the radial direction. The plurality of second sprocket teeth 71 includes at least one second reference tooth 73 and at least one chain retaining tooth 75 .

As shown in FIG. 4 , the at least one second reference tooth 73 is configured to first disengage from the inner link plate 3 a of the bicycle chain 3 in a downshift operation. For example, in a downshifting operation, the at least one second reference tooth 73 is first away from the pair of inner link plates 3 a of the bicycle chain 3 .

In this embodiment, as shown in FIG. 5 , at least one second reference tooth 73 includes a plurality of second reference teeth 73a to 73j. The plurality of second reference teeth 73a to 73j respectively correspond to the plurality of first reference teeth 62a to 62j. At least one chain holding tooth 75 comprises, for example, a set of chain holding teeth 75h1, 75h2, 75h3 shown in FIG. 4 and is prepared for each of the plurality of second reference teeth 73a to 73j shown in FIG. .

As shown in FIG. 4 , at least one chain holding tooth 75 is configured to hold an inner link plate 3 a of the bicycle chain 3 . For example, at least one chain holding tooth 75 is configured to hold the pair of inner link plates 3a of the bicycle chain 3 during a downshifting operation.

The at least one chain holding tooth 75 is configured to be positioned at a downstream side of the at least one second reference tooth 73 with respect to a drive rotation direction R1 of the front sprocket assembly 34 such that the at least one chain holding tooth 75 is from at least one One of the even-numbered teeth of the second reference tooth 73 .

The transmission rotation direction R1 is one rotation direction that the front sprocket assembly 34 rotates to move the bicycle 1 forward. One center of the transmission rotation direction R1 is defined on the rotation center axis X1.

For example, the at least one chain holding tooth 75 is one of the second tooth 75h1 , a fourth tooth 75h2 and a sixth tooth 75h3 of the at least one second reference tooth 73 .

Preferably, the at least one chain holding tooth 75 is derived from the fourth tooth 75h2 of the at least one second reference tooth 73 .

Specifically, if the at least one chain holding tooth 75 is selected from the second tooth 75h1, the fourth tooth 75h2 and the sixth tooth 75h3, the at least one chain holding tooth 75 is preferably the fourth tooth from the at least one second reference tooth 73 75h2.

Preferably, at least one chain holding tooth 75 comprises a plurality of chain holding teeth. The plurality of chain holding teeth includes at least two teeth from the second tooth 75h1 , the fourth tooth 75h2 and the sixth tooth 75h3 of the at least one second reference tooth 73 .

More preferably, at least one chain holding tooth 75 comprises at least three chain holding teeth 75 . The at least three chain holding teeth 75 respectively comprise at least a second tooth 75h1 , a fourth tooth 75h2 and a sixth tooth 75h3 from the at least one second reference tooth 73 .

As shown in FIG. 6, at least one chain retaining tooth 75 has a tooth tip 75a, an axially outward chamfer 75b disposed to the second axially outward surface 65, and an axially outward chamfer 75b disposed to the second axially inward surface 67. An axially inward chamfer 75c. For example, each of the plurality of chain retaining teeth 75 includes a tooth tip 75a, an axially outward chamfer 75b, and an axially inward chamfer 75c.

As shown in FIG. 6 , the axially outward chamfer 75b extends radially inwardly from the tooth tip 75a to an outwardly chamfered end 75e1 relative to the rotation center axis X1 . The outwardly chamfered end 75e1 is the point or line where the axially outwardly chamfered 75b begins to slope on the second axially outwardly surface 65 towards the tooth tip 75a. The axially outward chamfer 75b is disposed radially outward from the outwardly chamfered end 75e1 with respect to the rotation center axis X1.

As shown in FIG. 6 , the axially inwardly chamfered 75 c extends radially inwardly from the tooth tip 75 a to an inwardly chamfered end 75 e 2 relative to the rotation center axis X1 . The inwardly chamfered end 75e2 is the point or line where the axially inwardly chamfered 75c begins to slope on the second axially inwardly facing surface 67 towards the tooth tips 75a.

The inwardly chamfered end 75e2 is disposed radially outward from the outwardly chamfered end 75e1 with respect to the rotation center axis X1. Specifically, when the chain holding tooth 75 is viewed in the circumferential direction with respect to the rotation center axis X1, the inwardly chamfered end 75e2 is disposed radially outward from the outwardly chamfered end 75e1.

As shown in FIG. 7, if at least one first reference tooth 62 first engages with one of the inner link plates 3a1 of the bicycle chain 3 in a downshift operation in which the bicycle chain 3 is shifted from the second sprocket 53 toward the first sprocket 51 meshing, the chain tension between the at least one first reference tooth 62 and the at least one second reference tooth 73 can be increased.

When the chain tension between the at least one first reference tooth 62 and the at least one second reference tooth 73 increases during a downshift operation, the other inner chain plate 3a2 of the bicycle chain 3 tends to abut against the second sprocket tooth 71 The second axially inward surface 67 .

Specifically, when the chain tension between the at least one first reference tooth 62 and the at least one second reference tooth 73 increases during a downshift operation, the inner link plate 3a2 of the bicycle chain 3 tends to abut against the chain plate 3a2 from the at least one first reference tooth. The second axially inner surface 67 of the second tooth 75h1 , the fourth tooth 75h2 and the sixth tooth 75h3 of the two reference teeth 73 .

Specifically, when the chain tension between the at least one first reference tooth 62 and the at least one second reference tooth 73 increases during a downshift operation, the inner link plate 3a2 of the bicycle chain 3 is held firmly against the fourth tooth 75h2 The second axially inward surface 67 .

According to the present invention, as shown in FIG. 6, a chain contact area of the second axially inner surface 67 of the at least one chain holding tooth 75 is sufficiently obtained because the at least one chain holding tooth 75 is designed such that the inwardly chamfered end 75e2 It is arranged radially outward from the outwardly chamfered end 75e1 with respect to the rotation center axis X1. Therefore, at least one chain holding tooth 75 effectively holds the inner chain plate 3a of the bicycle chain 3 until the downshifting operation is completed.

A first radial distance D1 is defined radially from the inwardly chamfered end 75e2 to the outwardly chamfered end 75e1 with respect to the rotation center axis X1. Specifically, the first radial distance D1 is defined as a distance between the inwardly chamfered end 75e2 and the outwardly chamfered end 75e1 in the radial direction relative to the rotation center axis X1.

The first radial distance D1 is equal to or greater than 1.0 mm. The first radial distance D1 is equal to or smaller than 2.0 mm. In this embodiment, for example, the first radial distance D1 is 1.5 mm.

As shown in FIG. 4 , the second sprocket 53 has a bottom circle T1 . As shown in FIG. 5 , a second radial distance D2 is defined radially from the tooth bottom circle T1 to the inwardly chamfered end 75e2 relative to the rotation center axis X1. Specifically, the second radial distance D2 is defined as a distance between the tooth bottom circle T1 and the inwardly chamfered end 75e2 in the radial direction relative to the rotation center axis X1.

The second radial distance D2 is equal to or greater than 3.0 mm. The second radial distance D2 is equal to or less than 5.0 mm. In this embodiment, for example, the second radial distance D2 is 3.9 mm.

1: Bicycle 3: Bicycle chain 3a: Inner chain plate 3a1: Inner chain plate 3a2: Inner chain plate 3b: Bicycle chain roller 5: Bicycle frame 6: Seat tube 7: handle 9: Front wheel 9a: Front tire 11: rear wheel 11a: rear tire 13: Shift operating device 15: Drive train 17: front fork 18: Bicycle front hub assembly 19:Bicycle rear hub assembly 21: Bicycle Front Derailleur 23: Bicycle Rear Derailleur 25: crank assembly 27:Bicycle rear sprocket assembly 31: crankshaft 33: crank arm 34: Front sprocket assembly 35: Left crank arm 37: Right crank arm 39: Arm body 41: Sprocket installation part 46: Fixed member 51: First sprocket 53: Second sprocket 55: First axially outward surface 57: first axially inward surface 59: The first sprocket body 61: 1st sprocket tooth 62: First reference tooth 62a: Non-transmission face 62a to 62j: first reference teeth 65: Second axially outward surface 67: Second axially inward surface 69: Second sprocket body 71: Second sprocket tooth 73: Second reference tooth 73a to 73j: second reference teeth 75: Chain retaining teeth 75a: tooth tip 75b: Axially outward chamfer 75c: Axial inward chamfer 75e1: Outward chamfered end 75e2: Inwardly chamfered end 75h1: Chain retaining teeth 75h2: Chain retaining teeth 75h3: Chain retaining teeth D1: The first radial distance D2: second radial distance P1: Diameter of the first pitch circle P2: Diameter of the second segment circle R1: transmission rotation direction T1: tooth bottom circle X1: Rotation center axis

Selected embodiments of the technology will now be explained with reference to the accompanying drawings which form a part hereof, in which:

Fig. 1 is a side view of a bicycle according to an embodiment of the present invention;

Fig. 2 is a perspective view of a crank assembly according to an embodiment of the present invention;

Fig. 3 is a front view of a crank assembly according to an embodiment of the present invention;

Fig. 4 is a rear view of the crank assembly according to an embodiment of the present invention;

Fig. 5 is a rear view of the crank assembly according to an embodiment of the present invention;

Fig. 6 is a sectional view of a second sprocket cut by a cutting line VI of Fig. 4; and

Fig. 7 is a schematic diagram when viewing a first sprocket, a second sprocket and a bicycle chain from its upper side.

37: Right crank arm

53: Second sprocket

65: Second axially outward surface

67: Second axially inward surface

69: Second sprocket body

71: Second sprocket tooth

75: Chain retaining teeth

75a: tooth tip

75b: Axially outward chamfer

75c: Axial inward chamfer

75e1: Outward chamfered end

75e2: Inwardly chamfered end

D1: The first radial distance

D2: second radial distance

T1: tooth bottom circle

X1: Rotation center axis

Claims (18)

A front sprocket assembly (34) for a human vehicle, the front sprocket assembly (34) comprising: A first sprocket (51), which has a first axially outward surface (55) and is arranged on the first axially outward surface ( 55) a first axially inward surface (57) on one opposite side, the first sprocket (51) comprising: a first sprocket body (59); and A plurality of first sprocket teeth (61), which extend radially outward from a first outer periphery of the first sprocket body (59) in a radial direction relative to the rotation center axis (X1) and comprising at least one first reference tooth (62); and A second sprocket (53), which has a second axially outward surface (65) and a second an axially inward surface (67), the second axially inward surface (67) configured to face the first chain in the axial direction in an assembled state of the front sprocket assembly (34) The first axially outward surface (55) of wheel (51), the second sprocket (53) comprises: a second sprocket body (69); and A plurality of second sprocket teeth (71) extending radially outward from a second outer periphery of the second sprocket body (69) in the radial direction and including at least one second reference tooth (73 ) and at least one chain retaining tooth (75); The first sprocket (51) has a first pitch circle diameter (P1); The second sprocket (53) has a second pitch diameter (P2) larger than the first pitch diameter (P1), the second sprocket (53) is adjacent to the first sprocket (51) and there is no other sprocket between the first sprocket (51) and the second sprocket (53) in the axial direction; The at least one first reference tooth (73) is configured to first engage the the chain (3) is engaged such that a non-drive surface (62a) of the at least one first reference tooth (73) is in contact with a chain roller of the chain (3); The at least one second reference tooth (71) is configured to disengage first an inner link plate (3a) of the chain (3) during the downshifting operation; The at least one chain retaining tooth (75) is configured to be positioned at a downstream side of the at least one second reference tooth (73) with respect to a drive rotation direction (R1) of the front sprocket assembly (34), such that the at least one chain holding tooth (75) is an even numbered tooth of the at least one second reference tooth (73); The at least one chain retaining tooth (75) has a tooth tip (75a), an axially outward chamfer (75b) disposed to the second axially outward surface (65) and One of the inner surfaces (67) is axially inwardly chamfered (75c); The axially outward chamfer (75b) extends radially inwardly from the tooth tip (75a) to an outwardly chamfered end (75e1) relative to the rotation center axis (X1); The axially inward chamfer (75c) extends radially inwardly from the tooth tip (75a) to an inwardly chamfered end (75e2) relative to the rotational center axis (X1); and The inwardly chamfered end (75e2) is disposed radially outwardly from the outwardly chamfered end (75e1) with respect to the rotational center axis (X1). As before the sprocket assembly (34) of request item 1, wherein a first radial distance (D1) is defined radially relative to the rotational center axis (X1) from the inwardly chamfered end (75e2) to the outwardly bevelled end (75e1); and The first radial distance (D1) is equal to or greater than 1.0 mm. As before the sprocket assembly (34) of request item 2, wherein The first radial distance (D1) is equal to or smaller than 2.0 mm. The sprocket assembly (34) before any one of claim items 1 to 3, wherein The second sprocket (53) has a bottom circle (T1); a second radial distance (D2) is defined radially from the tooth base circle (T1) to the inwardly chamfered end (75e2) relative to the rotational center axis (X1); and The second radial distance (D2) is equal to or greater than 3.0 mm. As the sprocket assembly (34) before the request item 4, wherein The second radial distance (D2) is equal to or smaller than 5.0 mm. The sprocket assembly (34) before any one of claim items 1 to 3, wherein The at least one chain holding tooth (75) is configured to hold an inner link plate (3a) of the chain (3). The sprocket assembly (34) before any one of claim items 1 to 3, wherein The at least one chain holding tooth (75) is one of a second tooth (75h1), a fourth tooth (75h2) and a sixth tooth (75h3) from the at least one second reference tooth (73). As the sprocket assembly (34) before the request item 7, wherein The at least one chain holding tooth (75) is a fourth tooth (75h2) from the at least one second reference tooth (73). The sprocket assembly (34) before any one of claim items 1 to 3, wherein the at least one chain retaining tooth (75) comprises a plurality of chain retaining teeth (75); and The plurality of chain holding teeth (75) comprises at least two teeth from a second tooth (75h1), a fourth tooth (75h2) and a sixth tooth (75h3) from the at least one second reference tooth (73) . The sprocket assembly (34) before any one of claim items 1 to 3, wherein the at least one chain retaining tooth (75) comprises at least three chain retaining teeth (75); and The at least three chain holding teeth (75) respectively include at least a second tooth (75h1), a fourth tooth (75h2) and a sixth tooth (75h3) from the at least one second reference tooth (73). The sprocket assembly (34) before any one of claim items 1 to 3, wherein The first sprocket (51) has a first total number of teeth; The second sprocket (53) has a second total number of teeth that is one greater than the first total number of teeth. As the sprocket assembly (34) before claim item 11, wherein A tooth number difference between the first total number of teeth and the second total number of teeth is equal to or greater than 9. As the sprocket assembly (34) before claim item 11, wherein The difference in the number of teeth between the first total number of teeth and the second total number of teeth is equal to or less than 20. As the sprocket assembly (34) before claim item 11, wherein The second total number of teeth is in the range from 48 to 58. As the sprocket assembly (34) before claim item 11, wherein The first total number of teeth is in the range from 31 to 44. As the sprocket assembly (34) before claim item 11, wherein The at least one first reference tooth (62) is configured to first engage with the One of the inner chain plates (3a) of the chain (3) engages. A front sprocket assembly (34) for a human vehicle, the front sprocket assembly (34) comprising: A first sprocket (51), which has a first axially outward surface (55) and is arranged on the first axially outward surface ( 55) a first axially inward surface (57) on one opposite side, the first sprocket (51) comprising: a first sprocket body (59); and A plurality of first sprocket teeth (61), which extend radially outward from a first outer periphery of the first sprocket body (59) in a radial direction relative to the rotation center axis (X1) and comprising at least one first reference tooth (62); and A second sprocket (53), which has a second axially outward surface (65) and a second an axially inward surface (67), the second axially inward surface (67) configured to face the first chain in the axial direction in an assembled state of the front sprocket assembly (34) The first axially outward surface (55) of the wheel (51), the second sprocket (53) comprises: a second sprocket body (69); and A plurality of second sprocket teeth (71) extending radially outward from a second outer periphery of the second sprocket body (69) in the radial direction and including at least one second reference tooth (73 ) and at least one chain retaining tooth (75); The first sprocket (51) has a first pitch circle diameter (P1); The second sprocket (53) has a second pitch diameter (P2) larger than the first pitch diameter (P1), the second sprocket (53) is adjacent to the first sprocket (51) and there is no other sprocket between the first sprocket (51) and the second sprocket (53) in the axial direction; The at least one first reference tooth (62) is configured to first engage the the chain (3) is engaged such that a non-drive face of the at least one first reference tooth (62) is in contact with a chain roller of the chain (3); The at least one second reference tooth (73) is configured to disengage first an inner link plate (3a) of the chain (3) during the downshifting operation; The at least one chain retaining tooth (75) is configured to be positioned at a downstream side of the at least one second reference tooth (73) with respect to a drive rotation direction (R1) of the front sprocket assembly (34), such that the at least one chain holding tooth (75) is an even numbered tooth of the at least one second reference tooth (73); The at least one chain retaining tooth (75) has a tooth tip (75a), an axially outward chamfer (75b) disposed to the second axially outward surface (65) and One of the inner surfaces (67) is axially inwardly chamfered (75c); The axially outward chamfer (75b) extends radially inwardly from the tooth tip (75a) to an outwardly chamfered end (75e1) relative to the rotation center axis (X1); The axially inwardly chamfered (75c) extends radially inwardly from the tooth tip (75a) to an inwardly chamfered end (75e2) relative to the rotation center axis (X1); The second sprocket (53) has a bottom circle (T1); a radial distance is defined radially relative to the rotation center axis (X1) from the tooth base circle (T1) to the inwardly chamfered end (75e2); and The radial distance is equal to or greater than 3.0 mm. As the sprocket assembly (34) before claim item 17, wherein This radial distance (D2) is equal to or less than 5.0 mm.

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